Andrew A. Palladino

Mechanism of Hyperinsulinism in Short-chain 3-Hydroxyacyl-CoA Dehydrogenase Deficiency Involves Activation of Glutamate Dehydrogenase

The mechanism of insulin dysregulation in children with hyperinsulinism associated with inactivating mutations of short-chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD) was examined in mice with a knock-out of the hadh gene (hadh−/−). The hadh−/− mice had reduced levels of plasma glucose and elevated plasma insulin levels, similar to children with SCHAD deficiency. hadh−/− mice were hypersensitive to oral amino acid with decrease of glucose level and elevation of insulin. Hypersensitivity to oral amino acid in hadh−/− mice can be explained by abnormal insulin responses to a physiological mixture of amino acids and increased sensitivity to leucine stimulation in isolated perifused islets. Measurement of cytosolic calcium showed normal basal levels and abnormal responses to amino acids in hadh−/− islets. Leucine, glutamine, and alanine are responsible for amino acid hypersensitivity in islets. hadh−/− islets have lower intracellular glutamate and aspartate levels, and this decrease can be prevented by high glucose. hadh−/− islets also have increased [U-14C]glutamine oxidation. In contrast, hadh−/− mice have similar glucose tolerance and insulin sensitivity compared with controls. Perifused hadh−/− islets showed no differences from controls in response to glucose-stimulated insulin secretion, even with addition of either a medium-chain fatty acid (octanoate) or a long-chain fatty acid (palmitate). Pull-down experiments with SCHAD, anti-SCHAD, or anti-GDH antibodies showed protein-protein interactions between SCHAD and GDH. GDH enzyme kinetics of hadh−/− islets showed an increase in GDH affinity for its substrate, α-ketoglutarate. These studies indicate that SCHAD deficiency causes hyperinsulinism by activation of GDH via loss of inhibitory regulation of GDH by SCHAD.

The hyperinsulinism/hyperammonemia syndrome

The hyperinsulinism/hyperammonemia (HI/HA) syndrome is the second most common form of congenital hyperinsulinism (HI). Children affected by this syndrome have both fasting and protein sensitive hypoglycemia combined with persistently elevated ammonia levels. Gain of function mutations in the mitochondrial enzyme glutamate dehydrogenase (GDH) are responsible for the HI/HA syndrome. GDH is expressed in liver, kidney, brain, and pancreatic beta-cells. Patients with the HI/HA syndrome have an increased frequency of generalized seizures, especially absence-type seizures, in the absence of hypoglycemia. The hypoglycemia of the HI/HA syndrome is well controlled with diazoxide, a KATP channel agonist. GDH has also been implicated in another form of HI, short-chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD) deficiency associated HI. The HI/HA syndrome provides a rare example of an inborn error of intermediary metabolism in which the effect of the mutation on enzyme activity is a gain of function.

Clinical Features of Three Girls With Mosaic Genome-Wide Paternal Uniparental Isodisomy

Here we describe three subjects with mosaic genome‐wide paternal uniparental isodisomy (GWpUPD) each of whom presented initially with overgrowth, hemihyperplasia (HH), and hyperinsulinism (HI). Due to the severity of findings and the presence of additional features, SNP array testing was performed, which demonstrated mosaic GWpUPD. Comparing these individuals to 10 other live‐born subjects reported in the literature, the predominant phenotype is that of pUPD11 and notable for a very high incidence of tumor development. Our subjects developed non‐metastatic tumors of the adrenal gland, kidney, and/or liver. All three subjects had pancreatic hyperplasia resulting in HI. Notably, our subjects to date display minimal features of other diseases associated with paternal UPD loci. Both children who survived the neonatal period have displayed near‐normal cognitive development, likely due to a favorable tissue distribution of the mosaicism. To understand the range of UPD mosaicism levels, we studied multiple tissues using SNP array analysis and detected levels of 5–95%, roughly correlating with the extent of tissue involvement. Given the rapidity of tumor growth and the difficulty distinguishing malignant and benign tumors in these GWpUPD subjects, we have utilized increased frequency of ultrasound (US) and alpha‐fetoprotein (AFP) screening in the first years of life. Because of a later age of onset of additional tumors, continued tumor surveillance into adolescence may need to be considered in these rare patients.

A specialized team approach to diagnosis and medical versus surgical treatment of infants with congenital hyperinsulinism

Hyperinsulinism (HI) is the most common cause of transient and permanent forms of hypoglycemia in infancy. Establishing the correct diagnosis and initiating appropriate therapy without delay is of utmost importance. Once the diagnosis is made and if medical therapy with diazoxide fails, one should assume that the infant has a K(ATP) channel defect and may require surgery. In this case, the infant should be referred to a center that specializes in HI with 18-fluoro L-3,4-dihydroxyphenylalanine positron emission tomography scan. This report describes a center specializing in HI with a team of experts consisting of endocrinologists, nurse practitioners, geneticists, radiologists, pathologists, and a surgeon. It describes the centers paradigm for managing severe HI on the basis of more than 250 cases of HI in the past 10 years, including the diagnosis of HI, medical options, genetics of HI, imaging in HI, the surgical approach to HI, and outcomes.

Increased glucagon-like peptide-1 secretion and postprandial hypoglycemia in children after Nissen fundoplication.

CONTEXT Postprandial hypoglycemia (PPH) is a frequent complication of Nissen fundoplication in children. The mechanism responsible for the PPH is poorly understood, but involves an exaggerated insulin response to a meal and subsequent hypoglycemia. We hypothesize that increased glucagon-like peptide-1 (GLP-1) secretion contributes to the exaggerated insulin surge and plays a role in the pathophysiology of this disorder. OBJECTIVE The aim of the study was to characterize glucose, insulin, and GLP-1 response to an oral glucose load in children with symptoms of PPH after Nissen fundoplication. DESIGN Ten patients with suspected PPH and a history of Nissen fundoplication and eight control subjects underwent a standard oral glucose tolerance test at The Childrens Hospital of Philadelphia. Blood glucose (BG), insulin, and intact GLP-1 levels were obtained at various time points. PARTICIPANTS Children ages 4 months to 13 years old were studied. MAIN OUTCOME MEASURES Change scores for glucose, insulin, and intact GLP-1 were recorded after an oral glucose tolerance test. RESULTS All cases had hypoglycemia after the glucose load. Mean BG at nadir (+/- sd) was 46.7 +/- 11 mg/dl for cases (vs. 85.9 +/- 21.3 mg/dl; P < 0.0005). Mean change in BG from baseline to peak (+/- sd) was 179.3 +/- 87.4 mg/dl for cases (vs. 57.8 +/- 39.5 mg/dl; P = 0.003). Mean change in BG (+/- sd) from peak to nadir was 214.4 +/- 85.9 mg/dl for cases (vs. 55.9 +/- 41.1 mg/dl, P < 0.0005). Mean change in insulin (+/- sd) from baseline to peak was 224.3 +/- 313.7 microIU/ml for cases (vs. 35.5 +/- 22.2 microIU/ml; P = 0.012). Mean change in GLP-1 (+/- sd) from baseline to peak was 31.2 +/- 24 pm (vs. 6.2 +/- 9.5 pm; P = 0.014). CONCLUSIONS Children with PPH after Nissen fundoplication have abnormally exaggerated secretion of GLP-1, which may contribute to the exaggerated insulin surge and resultant hypoglycemia.

Pancreatic head resection and Roux-en-Y pancreaticojejunostomy for the treatment of the focal form of congenital hyperinsulinism

PURPOSE To determine the outcome of patients who underwent pancreatic head resection and Roux-en-Y pancreaticojejunostomy to the remaining normal pancreatic body and tail for the treatment of a focal lesion in the pancreatic head causing congenital hyperinsulinism (HI). METHODS One hundred thirty-eight patients underwent pancreatic resection for focal HI between 1998 and 2010. Twenty-three patients in the group underwent pancreatic head resection and Roux-en-Y pancreaticojejunostomy. RESULTS There were 13 females and 10 males. Median age and weight at surgery were 8 weeks and 5.8 kg, respectively. Twenty-one patients had a near-total pancreatic head resection, and 2 patients had a pylorus-preserving Whipple procedure. The pancreaticojejunostomy anastomosis was performed with interrupted fine monofilament sutures such that the transected end of the pancreatic body was tucked within the end of the Roux-en-Y jejunal limb. Median hospital stay was 22 days. All patients were cured of HI. CONCLUSION We conclude that pancreatic head resection with Roux-en-Y pancreaticojejunostomy is a safe and effective procedure for the treatment of the HI patient with a large focal lesion in the pancreatic head that is not amenable to local resection alone.

The surgical management of insulinomas in children.

PURPOSE Insulinomas are rare pediatric tumors for which optimal localization studies and management remain undetermined. We present our experience with surgical management of insulinomas during childhood. METHODS A retrospective review was performed of patients who underwent surgical management for an insulinoma from 1999 to 2012. RESULTS The study included eight patients. Preoperative localization was successful with abdominal ultrasound, abdominal CT, endoscopic ultrasound, or MRI in only 20%, 28.6%, 40%, and 50% of patients, respectively. Octreotide scan was non-diagnostic in 4 patients. For diagnostic failure, selective utilization of 18-Fluoro-DOPA PET/CT scanning, arterial stimulation/venous sampling, or transhepatic portal venous sampling were successful in insulinoma localization. Intraoperatively, all lesions were identified by palpation or with the assistance of intraoperative ultrasound. Surgical resection using pancreas sparing techniques (enucleation or distal pancreatectomy) resulted in a cure in all patients. Postoperative complications included a pancreatic fistula in two patients and an additional missed insulinoma in a patient with MEN-1 requiring successful reoperation. CONCLUSIONS Preoperative tumor localization may require many imaging modalities to avoid unsuccessful blind pancreatectomy. Intraoperative palpation with the assistance of ultrasound offers a reliable method to precisely locate the insulinoma. Complete surgical resection results in a cure. Recurrent symptoms warrant evaluation for additional lesions.

Rare forms of congenital hyperinsulinism

Rare forms of congenital hyperinsulinism (CHI) are caused by mutations in GLUD1 (encoding glutamate dehydrogenase), GCK (encoding glucokinase), HADH (encoding for L-3-hydroxyacyl-CoA dehydrogenase), SLC16A1 (encoding the monocarboxylat transporter 1), HNF4A (encoding hepatocyte nuclear factor 4α) or UCP2 (encoding mitochondrial uncoupling protein 2). The clinical presentation is very heterogeneous in regards to age of onset, severity, and manner of symptoms, as well as the response to medical treatment. Special individual characteristics have to be accounted in diagnosis and treatment. Diazoxide is the first-line drug for the rare forms of CHI for long-term treatment but is not entirely effective in some of these rarer defects (GCK, MCT1). The use of diazoxide is often limited by side effects and the use of octreotide as second-line drug has to be considered. A near-total pancreatectomy is only reserved for patients with diffuse disease and resistance to medical treatment as a last resort. Patients with CHI should be managed by centers with a highly experienced team in diagnostic work-up and treatment of this disease.

Congenital hyperinsulinism in children with paternal 11p uniparental isodisomy and Beckwith–Wiedemann syndrome

Background Congenital hyperinsulinism (HI) can have monogenic or syndromic causes. Although HI has long been recognised to be common in children with Beckwith–Wiedemann syndrome (BWS), the underlying mechanism is not known. Methods We characterised the clinical features of children with both HI and BWS/11p overgrowth spectrum, evaluated the contribution of KATP channel mutations to the molecular pathogenesis of their HI and assessed molecular pathogenesis associated with features of BWS. Results We identified 28 children with HI and BWS/11p overgrowth from 1997 to 2014. Mosaic paternal uniparental isodisomy for chromosome 11p (pUPD11p) was noted in 26/28 cases. Most were refractory to diazoxide treatment and half required subtotal pancreatectomies. Patients displayed a wide range of clinical features from classical BWS to only mild hemihypertrophy (11p overgrowth spectrum). Four of the cases had a paternally transmitted KATP mutation and had a much more severe HI course than patients with pUPD11p alone. Conclusions We found that patients with pUPD11p-associated HI have a persistent and severe HI phenotype compared with transient hypoglycaemia of BWS/11p overgrowth patients caused by other aetiologies. Testing for pUPD11p should be considered in all patients with persistent congenital HI, especially for those without an identified HI gene mutation.

Measurement of tissue acyl-CoAs using flow-injection tandem mass spectrometry: acyl-CoA profiles in short-chain fatty acid oxidation defects

The primary accumulating metabolites in fatty acid oxidation defects are intramitochondrial acyl-CoAs. Typically, secondary metabolites such as acylcarnitines, acylglycines and dicarboxylic acids are measured to study these disorders. Methods have not been adapted for tissue acyl-CoA measurement in defects with primarily acyl-CoA accumulation. Our objective was to develop a method to measure fatty acyl-CoA species that are present in tissues of mice with fatty acid oxidation defects using flow-injection tandem mass spectrometry. Following the addition of internal standards of [(13)C(2)] acetyl-CoA, [(13)C(8)] octanoyl-CoA, and [C(17)] heptadecanoic CoA, acyl-CoAs are extracted from tissue samples and are injected directly into the mass spectrometer. Data is acquired using a 506.9 neutral loss scan and multiple reaction-monitoring (MRM). This method can identify all long, medium and short-chain acyl-CoA species in wild type mouse liver including predicted 3-hydroxyacyl-CoA species. We validated the method using liver of the short-chain-acyl-CoA dehydrogenase (SCAD) knock-out mice. As expected, there is a significant increase in [C(4)] butyryl-CoA species in the SCAD -/- mouse liver compared to wild type. We then tested the assay in liver from the short-chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD) deficient mice to determine the profile of acyl-CoA accumulation in this less predictable model. There was more modest accumulation of medium chain species including 3-hydroxyacyl-CoAs consistent with the known chain-length specificity of the SCHAD enzyme.